Field of the Invention
The present invention relates to a wireless power transmitting method and apparatus using dual-loop in-phase feeding to expand a receiving space and improve power transmission efficiency of a wireless power transmitting system.
Related Art
A technology of expanding a receiving space with high power efficiency is important for wireless power transmission. It is because a receiving space with high power efficiency can provide autonomy in position to a receiver, and address low power transmission efficiency that results from position error between a transmitting coil and a receiving coil.
The existing wireless power transmitting system employs a single feeding method in which a transmitter includes a single resonant coil and a receiver includes a single resonant coil. To solve this drawback, there has been proposed Korean Patent Publication No. 10-2013-0099576 (Published on Sep. 6, 2013), which relates to a wireless power transmission apparatus including a transmission feeding loop, a transmitter resonator configured to receive and transmit impedance matching and power using the transmission feeding loop, a relay resonator configured to have a resonant frequency identical with that of the transmitter resonator and store energy in a specific space by generating mutual resonance through a resonance characteristic with the transmitter resonator, and one or more reception resonators configured to receive the energy stored in the specific space.
However, the above-mentioned wireless power transmitting apparatus employs a dual-loop single feeding method by installing two transmitting resonant coils on both sides of a receiving resonant coil, wherein one of the two transmitting resonant coils has a shorted feeding loop and the other transmitting resonant coil has a normal feeding loop. In this case, if the two transmitting resonant coils are installed at great distance from each other, a receiving resonant coil is excited by one transmitting resonant coil having a feeding loop, and then the receiving resonant coil causes the other transmitting resonant coil, which is installed on the opposite direction and has a shorted loop, to be excited. Due to the sequential excitation, if the receiving resonant coil is positioned closer to a transmitting resonant coil having a shorted feeding loop, power transmission efficiency may be significantly reduced. It means the above-mentioned wireless power transmission apparatus have restraints of a receiving space.